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Find [tex]\frac{d y}{d x}[/tex] for [tex]y=\sqrt{u}[/tex] and [tex]u=x^2+5[/tex]. State your answer in terms of [tex]x[/tex] only.

[tex]\frac{d y}{d x} = [/tex]


Sagot :

To find [tex]\(\frac{d y}{d x}\)[/tex] for [tex]\(y = \sqrt{u}\)[/tex] and [tex]\(u = x^2 + 5\)[/tex], we can use the chain rule. The chain rule states that if a variable [tex]\(y\)[/tex] depends on a variable [tex]\(u\)[/tex], which in turn depends on a variable [tex]\(x\)[/tex], then the derivative of [tex]\(y\)[/tex] with respect to [tex]\(x\)[/tex] can be found using the formula:

[tex]\[ \frac{d y}{d x} = \frac{d y}{d u} \cdot \frac{d u}{d x} \][/tex]

Let's apply this step-by-step:

1. First, express [tex]\(y\)[/tex] in terms of [tex]\(u\)[/tex]:
[tex]\[ y = \sqrt{u} \][/tex]

2. Compute [tex]\(\frac{d y}{d u}\)[/tex]:
[tex]\[ \frac{d y}{d u} = \frac{d}{d u} (\sqrt{u}) = \frac{1}{2\sqrt{u}} \][/tex]

3. Now, express [tex]\(u\)[/tex] in terms of [tex]\(x\)[/tex]:
[tex]\[ u = x^2 + 5 \][/tex]

4. Compute [tex]\(\frac{d u}{d x}\)[/tex]:
[tex]\[ \frac{d u}{d x} = \frac{d}{d x} (x^2 + 5) = 2x \][/tex]

5. Finally, combine these results using the chain rule:
[tex]\[ \frac{d y}{d x} = \frac{d y}{d u} \cdot \frac{d u}{d x} = \frac{1}{2\sqrt{u}} \cdot 2x = \frac{2x}{2\sqrt{u}} = \frac{x}{\sqrt{u}} \][/tex]

Since [tex]\(u = x^2 + 5\)[/tex], substitute [tex]\(u\)[/tex] back in terms of [tex]\(x\)[/tex]:

[tex]\[ \frac{d y}{d x} = \frac{x}{\sqrt{x^2 + 5}} \][/tex]

Thus, the derivative [tex]\(\frac{d y}{d x}\)[/tex] is:

[tex]\[ \boxed{\frac{x}{\sqrt{x^2 + 5}}} \][/tex]